Fractionator



May 10, 1955 e. F. THOMAS FRACTIONATOR Filed June 12, 1951 .fiacizzjar 'earye Ffiomaa. Q} W1;

United States Patent 0 FRACTIONATOR George F. Thomas, Chicago, Ill., assignor to Prater Pulfitlarizer Company, Chicago, III., a corporation of arms Application June 12, 1951, Serial No. 231,089

8 Claims. (Cl. 209-139 The present invention relates to a fractionator unit.

More particularly, the invention relates to an improved pneumatic fractionator unit for separating relatively fine from relatively coarse particles of matter.

Fractionator units are used to separate diiferent sized particles of material, such as flour, molding clay, cement, etc., where it is necessary to control the size of particles making up a mass of the material within very close tolerances. With pneumatic fractionator units heretofore known, it is quite often diflicult to obtain the desired efliciency of separation or classification because of insuflicient operation on the material being separated. This condition exists partly because of the manner in which separation is efiected, and partly because of the lack of means for controlling the operation of such known pneumatic fractionator units While the unit is running.

It is therefore one object of the present invention to provide an improved pneumatic fractionator unit.

Another object of the invention is to provide an improved pneumatic fractionator unit incorporating a novel method of introducing separation air into the material being separated.

A further object of the invention is to provide an improved pneumatic fractionator unit wherein separation of the different sized particles of matter being classified is accomplished in a plurality of stages, and wherein the eificiency of separation can be controlled within very close tolerances.

A feature of the invention is the provision of a pneumatic fractionator unit comprising a conduit for the matter to be separated, the conduit having at least one opening formed about its periphery for introducing secondary air peripherally into the matter guided thereby to effect separation.

Still another feature of the invention is the provision of a pneumatic fractionator unit having a conduit for the matter to be separated extending through a plurality of chambers. In each of the chambers air is introduced peripherally into the conduit to eflect separation of the matter carried thereby, the amount of separation air introduced in each chamber or stage being subject to control whereby the efliciency of separation can be controlled to a very fine degree.

Other objects, features, and many of the attendant advantages of this invention will be appreciated readily as the same becomes understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein similar parts in each of the several figures are designated by the same reference numeral, and wherein:

Fig. 1 is a sectional view of an improved pneumatic fractionator unit constructed in accordance with the invention; and

Fig. 2 is a fragmentary plan view of the fractionator unit shown in Fig. 1.

' Referring now to Fig. 1 of the drawings, an improved pneumatic .fractionator unit constructed in accordance with the invention is shown. The fractionator unit includes a generally cylindrically shaped, hollow, sheet metal shell, indicated at 11 and comprising an upper larger diameter, cylindrical end portion 12, a, tapered middle portion 13, and a lower, smaller diameter, cylindrical portion 14, and a tapered, lower end portion 15. Lower end portion 15 has a centrally disposed opening 16 formed therein which is in longitudinal alignment with a centrally disposed opening 17 formed in the end of the upper end portion 12. Each of portions 12, 15 of the shell 11 are secured together by welding, or by bolts seated in co-acting flanges in the manner shown, and the joints effectively sealed against the entrance of air therethrough by gaskets. I

Secured within the shell 11 thus formed are a plurality of open-ended, frusto-conical, sheet metal members 18, 19, and 21. Frusto-conical member 18 has the larger diameter end thereof secured to the interior of the side walls of upper portion 12 of shell 11, with the smaller diameter open end thereof longitudinally aligned with the openings l6 and 17 in the ends of shell 11, and extending down intoand spaced from the larger diameter end of frusto-conical member 19. Frusto-conical member 19 is secured to the interior of the side walls of cylindrical portion 14 of shell 11 by means of a flange 22 formed around its small diameter end, and a flange plate 23, and is positioned within body 11 with its smaller diameter open end longitudinally aligned with each of the openings 16 and 17 in the end of shell 11, and with the smaller diameter open end of frusto-conical member 18. The smaller diameter end of frusto-conical member 19 is spaced from and concentrically surrounded by the larger diameter open end of frusto-conical member 21, which has its smaller diameter open end extending out through the opening 16 in the lower end portion 15 of shell 11. By reason of this construction, each of the frusto-conical members 18, 19, and 21 co-act to form a conduit extending through the length of the shell 11, and that has at least one opening formed around the periphery thereof.

The flange plate 23 which supports frusto-conical member 19 also serves to form a wall section that divides the middle cylindrical portion 14 of shell 11 into two chambers, a first upper chamber 24, and a second lower chamber 25. The first upper chamber 24 has an opening therein to which is connected an air supply pipe 26 having an air valve 27 therein, and the second lower chamber 25 has an opening therein to which is connected an air supply pipe 28 having an air valve 29.

Positioned in the opening 17 in the upper end of body 11 is an open-ended, tubular member 31 that extends out from, as well as into the interior of shell 11. The outer or upper end of tubular member 31 is adapted to be conducted to a low pressure area wherein a high vacuum exists, and the lower or inner end of the tubular member 31 extends down into proximity with frusto-conical member 18, and is tapered outwardly, as at 32, to form a funnel.

Upon connection of the upper end of tubular member 31 to a low pressure area, air is caused to flow through the air'valve 27, air supply pipe 26, chamber 24, through the peripheral opening defined by the overlapping concentric ends of the frusto-conical members 18 and 19, under the lip of frusto-conical member 18, and up into and out through the tubular member 31 in the manner indicated by the arrows. Likewise, air is caused to fiow through air valve 29, air supply pipe 23, chamber 25, through the peripheral opening defined by the overlapping concentric ends of each of the frusto-conical members 19 and 21, under the lip of frusto-conical member 19, and up into and out through the tubular member 31 in the manner indicated by the arrows. The amount of air flow through either chamber 24 or chamber 25 can be controlled separately by varying the position of either air valve 27 or air valve 29. Thus, it can be seen that the conduit formed by aligned frusto-conical members 18, 19, and 21 extends through a plurality of chambers, each of which is individually interconnected through peripheral openings with the interior of the conduit, and through which the flow of air can be controlled.

In operation, air having the material to be separately entrained therein is introduced through a tangential inlet 33 into cylindrical upper portion 12 of shell 11 with sufficient force to cause the same to tangentially swirl around the sides of the conduit formed by the frusto-conical members 18, 19, and 21 as it drops downwardly through the conduit due to gravity. This swirling action causes the particles of the matter to be separated to be drawn over against the side wall of the conduit by centrifugal force, thus separating the entrained air from the matter to be separated. As the matter to be separated spins downwardly toward the lower open end of frusto-conical member 18, it comes into contact with the secondary air entering through the peripheral opening between frustoconical members 18 and 19. Because of the low pressure area or vacuum to which the upper end of member 31 is connected, the secondary air entering through the valve 27 and chamber 24 sweeps under the lip of frusto-conical member 18, through the swirling matter to be separated, up through the stack formed by cylindrical member 31, and out into the low pressure area. As the secondary air sweeps under the lip of frusto-conical member 18 and cuts through the swirling particles to be separated, it removes the finer, lighter particles, and leaves the coarse, heavier particles to fall to the bottom of the unit, and to eventually discharge out through the lower, open end of frusto-conical member 21. As the material not carried out by the first separation drops toward the bottom of frusto-conical member 19, it again comes in contact with a secondary air stream entering through air valve 29, chamber 25, and the peripheral opening between frustoconical members 19 and 21. This secondary air sweeps under the lip of frusto-conical member 19, passing through the coarse matter as it drops, and claims any of the finer, lighter particles which were not separated out by the first stage of separation. The amount of air flowing through chambers 24, 25 can be controlled by adjusting the position of the air valves 27, 29. The air valves 27, 29 can be adjusted to provide optimum amounts of air for any particular material being separated, theyalve 27 being used to provide a coarse adjustment, and the valve 29 being used as a fine adjustment whereby substantially all of the finer, lighter particles of the material being separated may be removed out through the stack formed by tubular member 31. a

From the foregoing description, it can be appreciated that the invention provides an improved, pneumatic fractionating unit wherein the secondary air effecting separation is introduced peripherally into and through the matter as it swirls downwardly through a tubular guide member. Because of the manner in which the secondary air is injected through the matter being separated, a very etficient separation of the finer, lighter particles of the matter is effected. By reason of the provision of the two stages of separation, and the means for controlling the supply of sweeping or secondary air, the efiiciency of separation or classification can be controlled to a very fine degree.

Having thus described my invention, it is obvious that various immaterial modifications may be made in the same without departing from the spirit of my invention; hence, I do not wish to be understood as limiting myself to the exact form, construction, arrangement, and combination of parts herein shown and described, or uses mentioned.

What I claim as new and desire to secure by Letters Patent is:

l. A pneumatic fractionator comprising a vertically disposed generally cylindrical hollow shell having aligned openings in the upper and lower ends thereof, a first open-ended frusto-conical member having the larger diameter end thereof secured and sealed peripherally to the interior wall of said shell to form a first chamber and the opening of the smaller diameter end thereof aligned with the openings in said shell, a second open-ended frusto-conical member supported within said body with the larger diameter open end of said second frusto-conical member concentrically surrounding the smaller diameter open end of said first frusto-conical member forming an annular passageway and the smaller diameter open end of said second frusto-conical member being aligned with the openings in the end of said body, a flange plate secured to the outer periphery of said second frusto-conical member and to said body and sealably dividing the interior of said body into at least two additional chambers, each of said chambers having an opening therein, an air supply pipe having a control valve therein connected to each of said openings, a third open-ended conical member supported within said body with the larger diameter end thereof concentrically surrounding the smaller diameter end of said second frusto-conical member forming another annular passageway and having the smaller diameter end thereof protruding through the opening in the lower end of said body, said annular passageways ope'r atively connected to said chambers, said air supply pipe connected to each of said openings adapted to discharge air within its respective chamber to fiow upwardly therethrough and reverse its direction as it discharges through the annular passageway interconnecting contiguous frusto-conical members and the chamber contiguous thereto, a tubular member secured in the opening in the upper end of said body and extending upwardly out from and downwardly into said body, the downwardly extending end of said tubular member being flared outwardly in a funnel-shaped fashion and being spaced adjacent the smaller diameter open end of said first frusto-conical member, and means secured to the upper end of said shell for introducing the matter to be separated into said body in a tangentially swirling stream.

2. A fractionator comprising a generally cylindrical hollow shell having aligned openings in each of the ends thereof, first open-ended frusto-conical member having the larger diameter end thereof secured and sealed peripherally to the interior wall of said shell to form a first chamber and the opening of the smaller diameter end thereof aligned with the openings in said shell, a second openended frusto-conical member supported within said body with the larger diameter open end of said second frusto conical member concentrically surrounding the smaller diameter open end of said first frusto-conical member forming an annular passageway and the smaller diameter open end of said second frusto-conical member being aligned with the openings in the end of said body, a flange plate secured to the outer periphery of said second frustoconical member and to said body and sealably dividing the interior of said body into at least twoadditional chambers, each of said chambers having an opening therein, a third open-ended conical member supported within said .body with the larger diameter end thereof concentrically surrounding the smaller diameter end of said second frustoconical member forming another annular passageway and having the smaller diameter end thereof protruding through one of the openings in the end of said body, and a material supply pipe tangentially mounted on the end of said shell adjacent said first frusto-conical member and opening into said shell.

3. A pneumatic fractionator comprising a vertically disposed generally cylindrical hollow shell, a plurality of open-ended frusto-conical members supported within said body, said frusto-conical members including a hollow cylindrical portion at the bottom thereof of the same diameter as the lower end of each of the frusto-conical members and said frusto-conical members at their upper ends having hollow cylindrical portions of the same diameter as the upper end of each of the frusto-conical members, the lesser diameter cylindrical portion of each of said frusto-conical members being telescoped within the larger diameter cylindrical portion of the adjacent member with an annular cylindrical peripheral passageway provided between the concentrically arranged telescoped ends of said cylindrical portions, at least one closing wall section secured between one of said frusto-conical members and the interior of said body and dividing the interior of said body into a plurality of chambers, means connecting each of said chambers to a high pressure area, means connecting the upper end of said shell to a low pressure area, and means for introducing the particles to be separated into the upper end of said shell in a tangentially swirling stream.

4. A fractionator comprising a generally cylindrical hollow shell having an opening in the upper and lower ends thereof and an upper chamber adapted for introducing air and entrained particles to be separated, a plurality of open ended frusto-conical members supported within said hollow shell and operatively connected together and to said upper chamber, said frusto-conical members spaced from the hollow shell providing chambers, the lesser diameter ends of each of said frusto-conical members being telescoped within the larger diameter end of the adjacent member forming an annular peripheral passageway between the concentrically arranged telescoped ends of said members, at least one closing wall section operatively positioned between the lower of said frusto-conical members and the adjacent frusto-conical member thereabove operatively connected thereto and secured to said adjacent frusto-conical member and the interior of said body and dividing the interior of said body into a plurality of chambers, each of said chambers having an opening in the wall thereof for the admission of secondary air, a tubular member extending through the upper opening and into the uppermost of said fmsto-conical members, said tubular member forming an annular passage within said upper chamber operatively connected through the uppermost of said frusto-conical members to the interior of said tubular member, and conduit means for introducing air and entrained particles to be separated tangentially into said upper chamber, whereby said secondary air admitted through the openings in the walls of the fractionator is discharged through the annular peripheral passages between the concentrically arranged telescoped ends of said frustoconical members from the chambers formed between the frusto-conical members and the hollow shell.

5. A pneumatic fractionator unit comprising a vertically disposed conduit comprising a tubular member, the upper end of the tubular member connected to an area wherein a vacuum exists, said conduit including a series of frusto-conical members and having a plurality of peripheral annular openings formed thereby along the length thereof, said frusto-conical members including a hollow cylindrical portion at the bottom thereof of the same diameter as the lower end of each of the frusto-conical members, and each of said frusto-conical members at their upper ends having a hollow cylindrical portion of the same diameter as the upper end of each of the frusto-conical members, a plurality of chambers formed about said conduit, the complementally formed cylindrical portions of said frusto-conical members being telescoped together forming annular, axially extending passageways operatively connected to their respective chambers through the aforesaid peripheral openings, each of said chambers being individually interconnected with the interior of said conduit through a respective one of the peripheral openings therein, a plurality of air supply pipes, each of said air supply pipes being coupled to a respective one of said chambers and having a control valve therein, and means for introducing the material to be separated into said frac tionator unit in a tangentially swirling stream.

6. A pneumatic fractionator unit comprising a vertically disposed conduit comprising a tubular member, the upper end of the tubular member extending exteriorly of said unit and connected to a low pressure area, said conduit also comprising a series of inverted frusto-conical members and having at least one annular opening extending around the periphery thereof exposed to a high pressure area, said frusto-conical members including a hollow cylindrical portion at the bottom thereof of the same diameter as the lower end of each of the frusto-conical members, and each of said frusto-conical members at their upper ends having a hollow cylindrical portion of the same diameter as the upper end of each of the frustoconical members, said hollow cylindrical portions extending axially with respect to the frusto-conical members, the complementally formed cylindrical portions of said inverted frusto-conical members being telescoped together forming said annular opening, said annular opening forming an annular passageway between the cylindrical portions of contiguous frusto-conical members, said tubular member extending within one of said frusto-conical members to intermediate the ends of one of said frusto-conical members, and means for introducing the material to be separated into the upper end of said conduit in a tangentially swirling stream.

7. The combination with a fractionator for separating solid particles to be classified including a hollow shell, the upper end thereof having a tangential inlet through which the gaseous fluid containing the particles to be separated enters, or" a plurality of open-ended inverted frusto-conical members supported within said shell, said frustoconical members including a hollow cylindrical portion at the bottom thereof of the same diameter as the lower end of each of the frusto-conical members, and each of said frusto-conical members at their upper ends having a hollow cylindrical portion of the same diameter as the upper end of each of the frusto-conical members, the lesser diameter ends of each of said cylindrical portions of the frustoconical members being telescoped within the larger diameter end of the adjacent cylindrical portion with an annular passageway provided between the telescoped ends of said members, a tubular member having a funnel-shaped member extending axially within one of the frusto-conical members contiguous to the annular passageway, said tubular member adapted to be connected to a source of low pressure for withdrawing the fines, and means for controlling and supplying secondary air under pressure to the shell to be discharged vertically therethrough, and reversing its direction as it flows through the annular passageway to further entrain additional fines for discharge through the tubular member as the coarser particles under the action of gravity discharge through the frusto-conical members to the exterior of said fractionator.

8. The combination with a fractionator adapted to be connected to a source of low pressure at one end for withdrawing the fines from the particles to be separated in separating solid particles to be classified, including a hollow shell, the upper end thereof having a tangential inlet through which the gaseous fluid containing the particles to be separated enters, of two or more open-ended inverted frusto-conical members supported within said shell, the

lesser and larger diameter ends of each of said frustoconical members formed with a cylindrical portion, said cylindrical portions of contiguous frusto-conical members adapted to be telescoped providing an annular passageway between said frusto-conical members, means for controlling and supplying secondary air under pressure to the hollow shell to be discharged vertically therethrough, and reversing its direction as it flows through an annular passageway to again reverse its direction as it enters the cylindrical portion of lesser diameter of one of the frustoconical members forming the annular passageway so that it further entrains additional fines for discharge to the source of low pressure for withdrawing the fines as the coarser particles under the action of gravity discharge through the frusto-conical members to the exterior of said fractionator.

References Cited in the file of this patent UNITED STATES PATENTS Van Gelder July 19, 1892 Kluge Apr. 9, 1912 10 Stebbins Feb. 28, 1928 

